1. Technical Field of the Invention
The present invention relates to air cleaners and to intake air routing structure for use in a motorcycle or the like, and particularly to air cleaners which incorporate throttle bodies therein.
2. Background Art
As one example of a conventional air cleaner for a V-type engine, a structure has been known in which an air cleaner is disposed below a fuel tank and above the V bank of an engine including front and rear cylinders arranged in a V shape, an air cleaner element is provided in a central portion of the air cleaner elongate in the vertical direction (see, for example, Japanese Laid-open Patent No. 2002-160686).
In this known design, a dirty air side of the air cleaner housing, connected to a lower portion of the air cleaner element, is extended into the V bank on the lower side, and a downstream side end portion of an air guide pipe is connected to the unfiltered side of the housing.
During operation of this known air cleaner, outside air is taken in from the central lower side of the air cleaner, and the air is cleaned by the air cleaner element. The flow of the filtered air is branched to the front and rear sides, and the filtered air is fed downwardly into the front and rear cylinders through throttle bodies, having upper ends connected to outlets provided at front and rear portions of a bottom portion of the air cleaner.
As another example of a conventional air cleaner structure, an air cleaner structure has been known in which an inlet for introduced air is opened in a front wall of an air cleaner housing, and a rectifying member roughly V-shaped projecting to the opening portion side in plan view is provided on the unfiltered side in the air cleaner housing at a position fronting on the inlet (see Japanese Utility Model Publication No. Sho 64-1196).
In this known design, an intake duct connected to the inlet is extended toward the front side of the vehicle body, and the front end of the intake duct is opened downwards in the vicinity of a head pipe.
In addition, there has also been known an air cleaner structure in which a throttle body of an electronic fuel injection device is disposed at a V bank of a V-type engine, and an air cleaner is connected to an upper portion of the throttle body.
In the above-mentioned air cleaner structure, it is necessary to provide a space for laying out the air cleaner element between the front and rear outlets, and to provide a space sufficient for containing the unfiltered side between the front and rear throttle bodies. However, since the positions of the outlets and the layout of the throttle bodies are limited by the bank angle of the front and rear cylinders, there are a large number of limitations as to the air cleaner element and the unfiltered side. Therefore, an air cleaner structure with few limitations exerted by the bank angle of the front and rear cylinders is desired.
In addition, since an intake device is enlarged in size when injectors are spaced from each other in the front-rear direction with the air cleaner element therebetween, it is desired to render the intake device compact.
Further, when it is intended to enlarge the volume of the air cleaner upwards so as to secure the capacity of the air cleaner, the upward enlargement is restricted because the fuel tank is enlarged along the upper side of the air cleaner housing. Moreover, where the fuel tank covers the entire region of the upper surface of the air cleaner housing, a front end portion of the air cleaner housing must be recessed, and the capacity of the air cleaner is sacrificed accordingly. Therefore, a structure making it possible to easily secure the capacity of an air cleaner having the upper side thereof covered with a fuel tank is desired. Accordingly, it is an object of the present invention to meet these demands.
Although the known vehicular air cleaners are usable for their intended purposes, a need still exists in the art for an improved air management structure for a vehicle. In particular, there is a need for an improved air management structure including an air cleaner housing having a hollow plenum therein, and an air cleaner element disposed in the housing and spaced away from the plenum.